A noble earth-pony family, fallen somewhat on hard times, is killed in a mining accident. They leave behind a single male heir, who is in sore need of a guardian, and of protection. Celestia takes the young pony under her wing and delivers him not to ponies - not earth, unicorn or pegasus - but to a dragon, an ambassador, an old friend of hers.
Playing a game which may just be deadly to the uninformed, the dragon decides that the one path open to him to ensure the safety of his charge and to carry out his sworn duty, is to adopt.